RU2422235C1 - Method of producing grinding bodies - Google Patents

Abstract

FIELD: process engineering. ^ SUBSTANCE: invention relates to metal forming and may be used in producing grinding bodies for drum mills. Grinding bodies are formed in three passes. Said passes comprises swaging out, reverse extrusion and reduction. Reverse extrusion aims at producing barrel-like billet with ball-like bottom. Bottom outer diameter makes 0.9 to 0.92 of grinding body OD. Reduction is performed to produce hollow-ball billet with one bore. Bore diameter makes 0.3 to 0.4 of inner diameter of grinding body. ^ EFFECT: ruling out accumulation of inner strains in colliding grinding bodies. ^ 4 dwg, 2 tbl

Description

The invention relates to the processing of metals by pressure and can be used in the mining industry and the building materials industry for the manufacture of grinding media used as a tool for grinding various materials in drum mills.

The prior art methods for the production of grinding bodies in the form of balls with a diameter of 30 to 120 mm on ball rolling mills made of high alloy steels of the type SHX15 (Semenov EI "Technology and equipment forging and hot forging. M: Engineering, 1999, p. 313), as well as by casting into a chill mold (Poddubny AI, “The structure and properties of grinding balls of alloyed iron when casting into a chill mold.” Foundry, 1997, No. 3, p. 7).

The disadvantage of these methods is that when operating in ball mills as a result of collisions with each other and with plates located on the inner surface of the mill drum, grinding media are susceptible to cracking upon impact as a result of accumulation of internal stresses exceeding the tensile strength of the metal.

The problem is solved by the fact that in the method for producing a grinding body, the process of shaping a body of a spherical shape according to the invention is carried out in three transitions: precipitation; reverse extrusion; crimp, while the reverse extrusion is carried out to obtain a workpiece in the form of a glass with a spherical bottom, the outer diameter of which is 0.9 ... 0.92 of the outer diameter of the grinding body, and crimping is obtained until the grinding body is a hollow spherical shape with one hole, the diameter of which is 0.3 ... 0.4 of d, where d is the inner diameter of the grinding body.

The method of obtaining the grinding body is illustrated by drawings, where

figure 1 shows a diagram of the precipitation of the original billet;

figure 2 - scheme of basting holes for reverse extrusion;

figure 3 - diagram of the reverse extrusion;

figure 4 - crimp with obtaining a hollow grinding body.

A method of obtaining a grinding body is as follows.

The initial billet 1 with a volume equal to the volume of the grinding body is cut off on a press machine from a bar heated by shear cutting in the inductor and fed to the upsetting position. Said preform 1 is subjected to settlement between plates 2 to obtain preform 3, the diameter of which D0 is 0.99 from D1, the diameter of the preform obtained at the backward extrusion transition (Fig. 1). After, in the aforementioned blank 3, the bushing is squeezed out due to the force action of the punch 4 in the matrix 5 (FIG. 2), the cavity of which allows the punch to be centered for backward extrusion. The billet with basting 6 is removed from the matrix 5 due to the translational movement of the ejector 7. Next, the said billet with basting 6 is subjected to reverse extrusion due to the force of the punch 8 in the matrix 9 to obtain the billet in the form of a glass with a spherical bottom 10 (figure 3), external whose diameter D1 is 0.9 ... 0.92 of D - the outer diameter of the grinding body. The glass 10 is removed from the matrix 9 due to the translational movement of the ejector 11. The glass 10 is crimped in the matrices 12 and 13 to obtain a grinding body 14 of a hollow spherical shape with one hole, the diameter of which is 0.3 ... 0.4 from d, where d - the inner diameter of the grinding body (figure 4). The grinding body 14 is removed from the matrix 13 due to the translational movement of the ejector 15. The claimed technology allows to obtain a grinding body with a fine-grained structure, hollow with an opening.

The values of the intervals claimed in the claims are obtained experimentally (see Tables 1 and 2).

In the first experiment (Table 1) in the process of plastic deformation, a loss of stability occurs, which consists in the formation of a fold oriented inside the ball. In the fifth experiment, during the deformation process, a defect is formed in the form of a thickened burr, which is formed as a result of the metal flowing between the matrices before they close. A value in the range of 0.90 ... 0.92 is optimal.

Table 1 Experiment No. D1 / D Process stability one 0.89 - 2 0.90 + 3 0.91 + four 0.92 + 5 0.93 -

In the first experiment (Table 2), the grinding body has a rounded shape, however, in the lower hemisphere of the ball there is an increase in wall thickness at the last stage of crimping the upper hemisphere, the obtained body has satisfactory resistance, but the circulation of the eroded substance through the hole into and out of the ball is difficult due to small size of the latter. In the fifth experiment, due to the enlarged hole, the grinding body has the shape of a truncated ball, the stability of the wall thickness of the ball is satisfactory, the resistance to fracture is reduced due to the high tendency for defects to appear during operation in the region of the end face of the truncated ball, circulation of the eroded substance through the hole to and from the ball high. The milled material that has fallen into the cavity of the ball partially compensates for the decrease in the mass of the hollow grinding body (in comparison with a solid grinding body). In the process, part of the material that has fallen into the cavity of the grinding body is poured out of it, and the other part, on the contrary, gets inside, thereby the material inside the cavity is constantly updated, which also contributes to its grinding. The value in the range of 0.3 ... 0.4 for the considered parameters is optimal.

The hollow structure with a hole and the fine-grained structure obtained as a result of intense plastic deformation of the technological process as a whole provide mainly elastic deformations in the grinding body during their collisions, thereby eliminating the possibility of accumulation of internal stresses in the metal, which ultimately allows to increase the resource of the above grinding body.

The features indicated in the independent claim are essential and interconnected with each other with the formation of a stable set of necessary features sufficient to obtain the required technical result.

table 2 Experiment number

Shape circle Ball wall thickness stability Fracture resistance Grinding material circulation Cumulative rate one 0.1 + - + - ± 2 0.2 + ± + - ± 3 0.3 + + + + + four 0.4 + + + + + 5 0.5 - + - + -

The relative diametric sizes stated in the claims are obtained empirically and are optimal, since the process is not ensured when exiting them.

Thus, the above information indicates the fulfillment of the following set of conditions when using the claimed technical solution:

- the object embodying the claimed technical solution, in its implementation is intended for the processing of metals by pressure, in particular, for the manufacture of grinding media used for grinding various materials in drum mills;

- for the claimed object in the form described in the independent clause of the formula below, the possibility of its implementation using the means and methods described above or known from the prior art on the priority date is confirmed;

- the object embodying the claimed technical solution, when implemented, is able to ensure the achievement of the technical result perceived by the applicant.

Therefore, the claimed subject matter meets the requirements of patentability “novelty”, “inventive step” and “industrial applicability” under applicable law.

Claims (1)

A method of producing a grinding body, including the process of shaping a spherical body, characterized in that the shaping is carried out in three transitions: by upsetting, reverse extrusion and crimping, the reverse extrusion is carried out to obtain a workpiece in the form of a glass with a spherical bottom, the outer diameter of which is 0 , 9 - 0.92 from the external diameter of the grinding body, and crimping - to obtain a grinding body of a hollow spherical shape with one hole, the diameter of which is 0.3 - 0.4 from d, where d is the internal diameter of the grinding body but.

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